Tire filled with lubricant coated cellular particles

ABSTRACT

A tire has its tire cavity filled with inexpensive lubricated light cellular particles and thereby avoids deformation and flattening of the tire upon loss of inflation pressure while maintaining vehicular control.

The present invention relates to improvements in tires. Moreparticularly, it concerns means intended to avoid the deformation andflattening of tires and the destruction or decrease in efficiency ofthem which results therefrom when the pressure inside the tire cavitybecomes insufficient.

The known devices of greater or lesser effectiveness, such as flexiblelinings or treads arranged on the inside of the tire cavity, show anumber of drawbacks, the main ones being their weight and thereforesensitivity to centrifugal force and the development of imbalance; theresistance to travel; the difficulties of implacement; and the highcost.

The object of the present invention is to overcome these drawbacks byproviding a means which makes it possible to maintain control of thevehicle, which is very light, is easy to put in place and isinexpensive.

The tire in accordance with the present invention, mounted with orwithout an inner tube on a wheel rim so as to form a tire cavity whichcan be inflated with a gas under pressure, is characterized by the factthat the tire cavity is filled at least partially with solid particlesof cellular material of very low apparent density but resistant to thestresses due to tire travel, these particles bearing a lubricant whichis inert with respect to the materials present in the tire cavity.

By "apparent density" there is understood not the density of thematerial of which the particles are formed but the density of theparticles expressed in g/dm³.

The invention relates to the use of particles of any shape or mixturesin all proportions of such particles whatever the law of distribution ofthe dimensions or shapes of the particles in the components of themixture. The invention also relates to the use of mixtures of particlessuch that the particles of at least one of the components of the mixtureare formed of a cellular material which is different from the materialconstituting the particles of the other component or components of themixture. It is advantageous to use particles of rounded shape when theyare easily available.

As material constituting the particles any known material or materialwhich becomes known in the future may be used provided that it satisfiesthe general definition given above. In the present state of knowledge,preference is given to the organic cellular polymers, for instance crosslinked or un-cross linked polyolefins, such as polyvinyl chlorides,polyethylenes, polypropylenes and their derivatives including thecopolymers of styrene such as the acrylics, as well as the cellularrubbers; polyurethanes; polyesters; derivatives of cellulose; foams ofpolyvinyl alcohol and formaldehyde; phenolic and epoxy resins;urea-formaldehyde resins; polyimides; polyamides; fluorinated polymers;polycarbonates; polyvinyl carbazoles; pyranyl foams from acrolein;phenylene polyoxides and polysulfones. Among them, expanded polystyreneis particularly suitable. However, the inorganic polymers such as thesilicones or the inorganic foams having a base of glass are alsosuitable, as are also cellular metal alloys of very low apparent densityhaving a base of aluminum, magnesium and beryllium, and the cellularrefractory materials of very low apparent density.

Satisfactory results have been obtained with particles which withstand agas pressure of at least 2 bars, are stable in shape up to a temperatureof about 80° C., are in the shape of spheres whose diameter, dependingon the material selected, is between about 1 mm. and about 8 mm. andhave an apparent density of less than about 100 g/dm³ and preferably ofthe order of 15 g/dm³ before the lubricant is added.

It is furthermore advantageous to use particles whose dimensions satisfya particle size distribution which varies within rather wide limits. Thepurpose of this is to have a certain content of particles of relativelysmall dimensions capable of plugging a possible hole in the tire, forinstance as a result of the penetration of a nail. These particles arethen drawn into the hole and assure at least the temporary air tightnessof the tire cavity.

The lubricant which is inert with respect to its environment whateverthe temperature, may for instance be fluid and/or solid or else becomefluid only when a given temperature is reached within the tire, forinstance when the tire cavity has suffered a decrease in pressure. It ismoreover advantageous to use a lubricant of high thermal conductivitywhich preferably increases with temperature so as to achieve heatexchange between the hottest element and the coldest element with whichthe particles enter into contact. It is also advantageous to combinesuch a lubricant with solid particles of one or more cellular materialswhose thermal conductivity increases with the temperature prevailingwithin the tire cavity.

Moreover, it is advantageous to use a lubricant which in liquid statehas a low vapor tension such that under the effect of the increase intemperature of the tire the pressure prevailing in the tire enclosureincreases as the lubricant evaporates. This may occur for instance as aresult of a decrease in the inflation pressure resulting from a leakcaused in the tire cavity or very simply in case of prolonged driving ofthe tire at high speed. The use of such a lubricant, borne by theparticles introduced into the tire, even in small amount, thereforemakes it possible to avoid taking the precaution of slightlyoverinflating the tire before starting a long trip at high speed, forinstance on a super highway. As a matter of fact, this recommendedadditional inflation pressure will be produced by the evaporation of thelubricant in the tire. Along this line, it is also advantageous to use alubricant formed of a mixture of a volatile liquid and a liquid of highboiling point.

Among the lubricants which are satisfactory, mention may be made of thepolyglycol ethers and their derivatives, obtained generally by theaction of ethylene oxide on compounds having one or more free hydrogenatoms, such as the alkyl phenols, the fatty alcohols and the fattyacids. The preferred lubricants are the polyethylene glycols and thepolypropylene glycols. Water can also be used, possibly mixed withanother lubricant, in view of its low vapor tension. The above-mentionedlubricants may advantageously be combined with solid lubricants such asgraphite, molybdenum disulfide or talc.

It goes without saying that in regions of the earth where thetemperature may be low and if the lubricant used is a liquid lubricant,it is advisable to select it with such characteristics that it does notfreeze at the lowest temperatures which may be reached. In view of theforegoing, the preferred lubricant should have a low freezing point, anappreciable cold vapor tension and a low heat of evaporation, so thatthe lubricated particles do not agglomerate when the tire is at astandstill.

When the tire is in normal state, the lubricated particles distributethemselves uniformly along the tire cavity of toroidal shape withoutforming any accumulation which could result in an imbalance. Theparticles themselves support the deformations upon tire travel, do notinterfere with each other and do not interfere with the deformations ofthe tire. The cost of the lubricated particles is remarkably low in viewof the negligible total amount of particles used to fill a tire cavity.Likewise, the amount of lubricant used may be very small in view of thevolume of the support consisting of the particles.

The invention contemplates the introduction of the particles into thetire cavity before or after they have been coated with the lubricant.

The extreme lightness of the particles makes their introduction into thetire cavity astonishingly easy, provided that one limits oneself toparticles of suitable size. For this purpose, a particle filling orificeis provided, on the one hand, on the tire cavity, said orifice abutting-- when the tire, of course, is mounted -- a tube which extends into areceptacle filled with particles. On the other hand, a vacuum-producingdevice known as a tube evacuator is mounted on the inflation valve ofthe tire cavity. When the tube evacuator is placed into action, theparticles, due to their lightness, are transferred by suction from thereceptacle into the tire cavity. Of course, a means to prevent theparticles from emerging from the tire cavity during the filling thereofis provided. When the suitable quantity of particles has beentransferred, the action of the tube evacuator is stopped, the tube isremoved from the filling orifice and the orifice is hermeticallyplugged. It is now merely necessary to inflate the tire cavity to thepressure of use of the tire. Such a filling can be effected even by anunskilled person, on a new tire as well as on an old tire, for instanceafter repair of a flat.

As a variant, the inflation valve can also be used to introduce theparticles into the tire cavity.

Another possibility of introducing particles into the tire cavity whenthe latter does not contain an inner tube consists first of all infilling one or more bags formed of a film of flexible and preferablyheat fusible material with said particles and then putting said bag orbags in the tire cavity during the mounting of the tire on the rim. Inorder to prevent the bag or bags from moving in the tire cavity,cementing to the inner wall of the tire, for instance in the region ofthe tread thereof, can be effected.

This method of introduction may be used whatever the type of wheel rim.However, it is particlarly advantageous in the event that the rim has atire mounting groove adjoining the rim flange located on the outer sidewith respect to the vehicle and which is plugged after the tire has beenput in place.

Such a rim is described for instance in U.S. patent application Ser. No.489,106, now Pat. No. 3,844,286. The advantage of using one or more bagswith this type of rim is that it is not necessary to provide the rimwith an orifice particularly intended to permit the introduction of theparticles into the tire cavity, as for instance when using the suctionfilling process described above.

The bag (or each of the bags) provided in accordance with the inventionin order to contain the particles is of preferably circular crosssection with a diameter substantially equal to the largest dimension ofthe tire cavity. The length of this bag or the total length of the bagscorresponds substantially to the mean circumferential length of the tirecavity.

The flexible material of which the bag or bags is made is, for instancea copolymer of ethylene and vinyl acetate in the form of a film, or anyother material of low softening point (for instance, about 65° C. orless) as defined in French Standard NF T-51-021 or in the American ASTMD 1525 65 T. There are preferred films whose thickness is not more thanabout 40μ formed of combinations of low density polyethylene andthermoplastic styrene-butadiene-styrene block copolymers, these filmshaving the advantage that they can be handled easily due to their goodmechanical and elastic properties at ambient temperature.

When the above-mentioned softening point is reached during the travel ofthe tire, the bag containing the particles softens and then melts sothat the particles enter directly into contact with the inner wall ofthe tire. If the latter has accidentally lost all or part of theinflation air, the driving can continue in normal manner.

The accompanying drawing and its description will facilitate anunderstanding of the invention. In this drawing, by way of illustrationand not of limitation:

FIG. 1 is a radial section view of a tire in which there is contained aninner tube filled with a charge of particles in accordance with theinvention;

FIG. 2 is a section view of a tire mounting comprising a device forfilling a tire in accordance with the invention;

FIG. 3 is a radial section view of a tire mounted on a wheel rim with aplugged mounting groove adjacent to one of the flanges of said rim;

FIG. 4 is a circumferential section view along the line IV--IV of FIG.3, on a smaller scale, showing the combination of the tire and its wheelrim with a bag containing particles in accordance with the invention,and

FIG. 5 is a circumferential section view of a mounted tire containingtwo bags instead of one.

Referring to FIG. 1, a tire 1 is mounted on the rim 2 of a wheel 3. Thistire 1 has an inner tube 4 provided with an inflation valve 5.

In accordance with the invention the tire cavity defined here by theinner tube 4 contains solid particles 6 of cellular material which beara lubricant. In this example, the inner tube is completely filled withsuch particles.

A device for filling a tire cavity with particles in accordance with theinvention is shown schematically in FIG. 2. This device comprises areceptable 20 containing particles 6 into which there extends one end ofa tube 21, the other end of which is connected to the tire 22 mounted onthe rim 23 of a wheel 24. This connection is effected in airtight mannerthrough the wall of the rim 23. A vacuum-producing device 27 of the typeknown as a tube evacuator is connected by a hose 26 to an inflationvalve 25 which is firmly connected with the rim. This device istraversed by a stream of air under pressure and has the effect ofaspirating the air contained in the tire 22. As the pressure decreasesin the tire, the particles 6 contained in the receptacle 20 are drawninto the tube 21 and fill the tire. The filling ceases as soon as theflow of air under pressure in the device 27 is interrupted.

When the desired degree of filling has been reached, the tube 21 iswithdrawn from the rim 23, the corresponding orifice in the rim isclosed by a suitable plug, for instance a threaded plug, whereupon theair suction device 26, 27 is disconnected from the valve 25 and a sourceof compressed air is connected to said valve thereby inflating the tire22 in customary manner up to the desired pressure.

A variant of this method of filling consists in using an airtightreceptacle 20 which contains a supply of particles and causing air underpressure to act on the particles. The tube evacuator 27 being eliminatedand the valve 25 being open, the excess pressure thus establishedtransfers the particles into the tire cavity.

The wheel equipped with the tire which has thus been filled and inflatedcan then be mounted on the vehicle.

The assembly shown in FIGS. 3 and 4 comprises a rim 31 having a circulargroove 32 intended to facilitate the mounting of the tire 33. Thisgroove 32 is adjacent to that one of the flanges of the rim 32 which isintended to be mounted on the outside with respect to the vehicle. Thegroove 32, after the beads 34 and 35 of the tire have been put in place,is closed, for instance, by means of a ring 36 which forms an axialextension of the rim well 37 and serves as airtight seat for the outerbead 35 of the tire. An inflation valve, not shown, is provided in theouter sidewall of the groove 32. In accordance with the invention, thetire cavity contains a filling of solid particles such as defined above,enclosed in a bag 39 of toroidal shape (See FIG. 4) of a length suchthat its ends 40, 40' are adjacent to each other within the tire cavity.The wall of this bag is of very small thickness, of the order of 40μ;for the clarity of the drawing this wall has been shown in relativelylarge thickness.

In the variant shown in FIG. 5, two bags 50, 51 adjacent to each otherhave been used instead of a single bag as in the case of FIG. 4.

It goes without saying, that the invention also extends to the use ofbags which are juxtaposed either in radial direction or incircumferential direction or in both directions of the tire at the sametime.

In all of the above examples, the products designated below by theirtrade name can be used to form the cellular particles:

    __________________________________________________________________________    TRADE NAME                                                                                FOAM OF       MANUFACTURER                                        __________________________________________________________________________    VINYLCEL  Cross linked rigid polyvinyl                                                                 Johns-Manville                                                 chloride                                                            ETHAFOAM  Polyethylene   Dow Chemical                                         NEOPOLEN  Cross linked polyethylene                                                                    B.A.S.F.                                             MINICEL PPF                                                                             Polypropylene  Haveg Industries Inc.                                STYROPOR P                                                                              Polystyrene    B.A.S.F.                                             STYROCELL Polystyrene    Shell                                                AFCOLENE  Polystyrene    Rhone-Progil                                         STYROPOR H                                                                              Poly (styrene acrylonitrile)                                                                 B.A.S.F.                                             NEOPRENE WRT                                                                            Polychloroprene                                                                              DuPont deNemours                                     CARIFLEX 1502                                                                           Styrene-butadiene                                                                            Shell                                                HYCAR 1001                                                                              Nitrile-butadiene                                                                            B.F. Goodrich                                        CARADOL   Flexible polyurethane                                                                        Shell                                                QUADROL   Semi-rigid polyurethane                                                                      Ugine-Kuhlmann                                       EKANATE   Rigid polyurethane                                                                           Ugine-Kuhlmann                                       LILENE      --           Ugine-Kuhlmann                                       ESTAFOAM  Polyester      Vanguard Products                                    BRL 2759  Phenol resin   Union Carbide                                        ECCOFOAM EFB                                                                            Epoxy resin    Emerson & Cuming                                     ISOCHAUM  Urea-formaldehyde resin                                                                      B.A.S.F.                                             VESPEL    Polyimide      DuPont deNemours                                     KINEL     Polyimide      DuPont deNemours                                     ECN Foamed                                                                              Polyamide      DuPont deNemours                                      Nylon                                                                        VITON A   Fluorinated polymer                                                                          DuPont deNemours                                     MAKROLON  Polycarbonate  Bayer                                                LEXAN     Polycarbonate  General Electric Corp                                POLECTON  Polyvinyl carbazole                                                                          GAF Corporation                                      LUVICAN M150                                                                            Polyvinyl carbazole                                                                          B.A.S.F.                                             KAYFAX    Pyranyl        I.C.I. American Inc.                                 NORYL     Phenylene polyoxide                                                                          General Electric Corp                                RTV 7     Silicone       General Electric Corp                                I.C.B. 3400                                                                             Refractory material                                                                          IPSEN Industries Inc.                                __________________________________________________________________________

The cellulose acetate foam produced by the Strux Corporation, thepolyvinyl alcohol and formaldehyde foam obtained from ELVANOL 73,125manufactured by DuPont deNemours and the aqueous formaldehyde andpolysulfone foam, described in Netherlands Pat. No. 66,03273, etc., arealso suitable.

What is claimed is:
 1. A tire mounted on a wheel rim so as to form atire cavity which can be inflated with a gas under pressure,characterized by the fact that the tire cavity is filled at leastpartially with solid light-weight discrete particles of cellularmaterial having a very low apparent density of less than about 100g./dm³ but resistant to stresses due to tire travel, said particlesbearing a lubricant which is inert with respect to the materials presentin the tire cavity, thus, the particles are free to move relative to oneanother, with low friction and low generation of heat when they have tocushion the tire after a puncture of the tire cavity and plug thepuncture hole.
 2. The tire according to claim 1 wherein the particleshave a rounded shape.
 3. The tire according to claim 1 wherein theparticles are selected from a cellular material of the group consistingof cross linked and uncross linked polyolefins, polyurethanes,polyesters, derivatives of cellulose, foams of polyvinyl alcohol andformaldehyde, phenolic resins, epoxy resins, urea-formaldehyde resins,polyimides, polyamides, fluorinated polymers, polycarbonates, polyvinylcarbazoles, pyranyl foams from acrolein, phenylene polyoxides andpolysulfones.
 4. The tire according to claim 3 wherein the particles areof expanded polystyrene.
 5. The tire according to claim 1 wherein theparticles are of a cellular metal alloy.
 6. The tire according to claim1 wherein the particles are of a cellular refractory material.
 7. Thetire according to claim 1 wherein the particles are of an inorganic foamhaving a base of glass.
 8. The tire according to claim 1 wherein theparticles are spheres whose diameter is between about 1 mm. and about 8mm., withstand a gas pressure of at least 2 bars and are stable in shapeup to a temperature of about 80° C.
 9. The tire according to claim 8wherein the particles have an apparent density of about 15 g/dm³. 10.The tire according to claim 1 wherein the particles are of a materialwhose thermal conductivity increases with temperature.
 11. The tireaccording to claim 1 wherein the lubricant is a solid which is inertwith respect to its environment and becomes fluid at a temperature aboveambient temperature.
 12. The tire according to claim 1 wherein thelubricant has a high thermal conductivity which increases withtemperature.
 13. The tire according to claim 1 wherein the lubricant inliquid state has a low vapor tension so as to evaporate at thetemperature of tire travel.
 14. The tire according to claim 1 whereinthe lubricant is a mixture of a volatile liquid and a liquid of highboiling point.
 15. The tire according to claim 1 wherein the lubricantis selected from the group consisting of polyglycol ethers and theirderivatives obtained by the action of ethylene oxide on compounds havingone or more free hydrogen atoms.
 16. The tire according to claim 1wherein the lubricant contains water.
 17. The tire according to claim 1wherein the tire cavity has, in addition to an inflation valve, aparticle filling orifice provided with a plug.
 18. A tire according toclaim 1 wherein the particles in the tire cavity are contained in atleast one bag, said bag being formed of a film of flexible material andhaving a circular cross section with a diameter substantially equal tothe largest dimension of the tire cavity, the length of said bag or thetotal length of said bags corresponding substantially to the meancircumferential length of the tire cavity.
 19. The tire according toclaim 18 wherein the bag film is a heat-fusible material having a lowsoftening point of below about 65° C.
 20. The tire according to claim 19wherein the bag film is a copolymer of ethylene and vinyl acetate. 21.The tire according to claim 18 wherein the bag is adhered to the innerwall of the tire.
 22. The tire according to claim 1 which is mounted ona wheel rim with a plugged mounting groove.
 23. The tire according toclaim 1 wherein the tire contains an inner tube.
 24. The tire accordingto claim 1 wherein the tire is a tubeless tire.